Tinkercad
We use the design/engineering cycle to do many projects in my class. One tool for design is Tinkercad. The free online site allows students to design objects. These designs can be viewed using the Object Viewer app for the Merge cube to check for flaws in the design. When complete the design can go to a 3D printer. It can also be uploaded into CoSpaces so it can be used in V.R. (virtual reality) or the Merge cube.
I designed the robot sent to our Moon Base using Tinkercad.